In many devices such as radar, free electron lasers, and other high energy radiation sources such as high powered millimeter or microwave devices, there is a need for providing a helically oriented transverse magnetic field. Such permanent magnetic devices are known, for example, the permanent magnetic structure disclosed in U.S. Pat. No. 4,764,743 entitled "Permanent Magnet Structures For The Production Of Transverse Helical Fields" issuing to Leupold et al on Aug. 16, 1988, which is herein incorporated by reference. Therein disclosed is a permanent magnet structure formed from a multiplicity of permanent magnet segments, with the segments displaced radially from each other progressively along the longitudinal axis. Another permanent magnet structure is disclosed in U.S. Pat. No. 4,994,778 entitled "Adjustable Twister" issuing to Leupold on Feb. 19, 1991, which is herein incorporated by reference. Therein disclosed is a permanent magnet structure comprising a linear array of hollow cylindrical flux source structures nested one within another about a common central axis and free to rotate about the axis providing a periodic magnetic structure suitable for use as a helical wiggler or a twister. Another permanent magnet structure is disclosed in U.S. Pat. No. 5,099,217 entitled "Constant Gap Cladded Twister" and issuing to Leupold on Mar. 24, 1992, which is herein incorporated by reference. Therein disclosed is a cladded magnet twister with each segment being displaced radially in equal angular segments along the central axis having a plurality of cladding magnets and opposing pole pieces having convex faces which are directed inward toward one another. While these prior permanent magnet structures produce a desired magnetic field within their central working space, they all have a relatively complex permanent magnet structure with a multitude of different magnets. Therefore, there is a need for a simpler permanent magnet structure having less volume and weight that produces a desirable transverse helical magnetic field.